Printing telegraph system



May 29, 1934. WATSON 1,960,360

PRINTING TELEGRAPH SYSTEM Filed May 12, 1933 FIG.

73 I3 FIG. 2

' I05 1/ 24 l? 25 V/Z ,8 a X 4 20 an 22 I m I2 60 27 28 INVENTOR E. EWATSON ATTORNEY Patented May 29, 1934 PRINTING TELEGRAPH SYSTEM EdwardFisk Watson, Larchmon't, N. Y., assigno'r to" American Telephone andTelegraph Com-- pany', a corporation of New York Application May 12,1933, Serial No. 670,794-

14 Claims.

This invention relates to printing telegraph systems and moreparticularly to an answerback device employed in connection therewith.

An object of this invention is to transmit automatically predeterminedsignals from a remotely controlled printer.

Another object of this invention is to provide means for injorming acalling subscriber in a printing telegraph or other signaling system of19 the identity of the responding station.

Another object of this invention is to apprise a calling subscriber thatconnection has been established to the correct called station.

Printing telegraph systems usually comprise a plurality of subscribersstations capable of interconnection with each other by means ofexchanges. Some of these stations have facilities for sending andreceiving messages, while others have merely provision for the reception20 of messages only. At times the sending of messages to unattendedreceiving stations is desirable. For this purpose, means are usuallyprovided by which either the operator at the central switchboard or thecalling subscriber can 5 start the motor at the called station.Frequently, the calling subscriber desires to know before transmittingthe message if connection has been established with the desired calledstation.

In accordance with this invention, an answerback designation isautomatically transmitted from the answering station either upon thereception of an inquiring signal from the calling station or wheneverthe motor at the called station is remotely started.

In general, the invention comprises an arrangement employed inconnection with the sending mechanism of the regular printer. Thearrangement, whether actuated by the signal from the calling station orby remotely starting the motor is adaptable to both sending-receivingprinters and receiving-only printers. An auxiliary set of discs islocated in close proximity with the contact cams. These discs, one foreach of the contact cams, are mounted on a common shaft. In addition tothe discs, an indent wheel and ratchet wheel are likewise mounted on theshaft. A pawl attached to the locking loop of the printer keyboard orcontact mechanism is so arranged that it is capable of engaging theratchet wheel and revolves the ratchet wheel one notch for thetransmission of one set of impulses by the sending cams. Levers incontact with the peripheries of the discs control and deter- 5: mine theposition of locking means. Locking means control instrumentalities forthe transmission of signals over the line. The peripheries of the discsare such that the desired message is transmitted over the line and areso arranged that the predetermined message can be sent 69 during onecomplete revolution of the discs. The proportional circumferentialsurface of the peripheries of the discs equivalent to that of one notchof the ratchet Wheel corresponds to the set of impulses for onecharacter. may be employed for the movement of the shaft other than thatof the ratchet wheel and pawl. For example, gears may be supplied whichturn the disc synchronously with the transmission of each set ofimpulses. When the locking 7 means of the printer are actuated after thetransmission of each set of impulses, the pawl moves the ratchet Wheelover one notch. As a result of this latter action the discs are movedfor the transmission of another set. In this 7 manner, the completeanswer-back message is transmitted. Means actuated by the movements of alever are provided for causing the pawl to engage the ratchet wheel. Themovement of this lever is produced by the inquiring signal feature isaccomplished by means which start the answer-back mechanism whenever themotor is started. When either modification is empiloyed, thetransmission of the answer-back message may be deferred until the motorhas attained sufiicient speed. Means at each station for disconnectingthe answer-back mechanism Whenever it is so desired and means fortransmitting the answer-back signal regardless of whether the keyboardis rendered inoperative are also provided.

A better understanding of the invention may be obtained by reference tothe accompanying drawing in which:

Fig. 1 shows a plan View of a fragment of a telegraph typewriter inwhich the essential parts necessary for an understanding of theinvention are illustrated;

Fig. 2 is a sectional View, slightly enlarged, of the device of Fig. 1along the line 2, 2 thereof;

Fig. 3 is a view partly in section of the device 119 Other means g g'ralpart of bus bar 102.

' over the line circuit.

of Fig. 1 along the line 3, 3 thereof together with a schematic ofapparatus and circuit associated with the parts shown:

Fig. 4 is a side elevation of the mechanism shown in Fig. 2;

Fig. 5 illustrates a modification of the invention by which theanswer-back mechanism is actuated when the motor is started;

Fig. 6 is a view of a portion of the modified mechanism shown in Fig. 5.

Referring to Fig. 1, the numerical designation 12 represents the mainframe of the telegraph typewriter. A plurality of rotatable contact cams35 to 39 are fixedly mounted on a rotatable shaft 80. Shaft 80 isrotated by driven clutch member 62 and driving clutch member 53 by theshaft 64 geared to the printer motor '71 by the gear '70. A plurality ofcontact levers to 49 in engageable relation respectively with contactearns 35 to 39 open and close respectively a plurality of transmittingcontacts to 59. The opening and closing of these contacts in variouscombinations transmit over a line circuit in ordered sequence a code ofimpulse representing each character of a message.

One of the contacts from each pair 55 to form an integral part of thebus bar 101, while theother of each pair of contacts are an inte- Bothbus bars are connected in series with the line circuit. Fixedly mountedon the, rotatable shaft 80 is a throwout cam 21". J A spring 103 theconvolution of which'jsur'rounds the shaft 80 affords sufficient v biasso that the driven clutch member 62 engages with the driving clutchmember 63 whenever the clutch throw-out lever 20, normally in engagementwith the throw-out cam 21, is disengaged therefrom. 7 Locking meanscomprising a plurality of locking levers 65 to 69 are associatedrespectively with contact levers 45 to 49. Each of the locking leverscontrols its respectively associated contact lever by either allowingthe contact lever to close its corresponding. contact when the camsrevolve or preventing that contact lever from dropping into the indentof the associated sending cam whereby the contact remains open. Astopstart cam 34 with its associated contact 54 is also shown. Theprinter motor '71 is driven at a constant speed and when the clutchthrow-out lever 20 is disengaged from the throw-out cam 21, drivenclutch member 62 engages with driving clutch member 63. The contact camsare rotated and the contacts corresponding to the contact'levers whichare unlatched by their respectively associated locking levers close,while those that are latched remain open. A series of impulses inordered sequence corresponding to the desired character to betransmitted is sent The impulses sent by one revolution of the shaftrepresent a single letter of a message. The apparatus above described iswell known to those skilled in the art.

a corresponding rotation of the discs 95 to 99.

The pawl is actuated by the movement of the locking loop 19. The lockingloop cam 18 produces a rocking motion of the looking loop, one movementfor the complete rotation of the shaft 80 or the transmission of onecharacter. As a result of the movement of the locking loop, the ratchetwheel steps the shaft 49, the radial distance corresponding to one notchof the ratchet wheel for each character transmitted. The pawl 11 isnormally not in engagement with the ratchet wheel 23 being held in aninoperative position by means of an element 19.

In Figs. 2 and 4, the details of the construction of the answer-backmechanism are more clearly shown. The pawl 11 rests upon the element 10.When the element'lO is moved in a downward position, the pawl engagesthe ratchet wheel 23. In engageable relationship with the element 10 isthe clutch throw-out lever 20. Both the throw-out lever 20 and theelement 10 are normally biased in an upward position respectively by thespring 30 and 24. Both springs are attached to the framework. 12. Adownward. motion of element 10 disengages the clutch throw-out lever 20from the throw-out cam 21. This latter disengagement results in therotation of the shaft 80. After a partial rotation of the shaft, thelocking loop 19 moves from the elevations of the periphery of thelocking loop cam 13. The locking loop latches the locking levers 65 to69 in a manner well known in the art. When the combination of impulsescorresponding to one character has been transmitted, the shaft 99 havingcompleted one revolution, the locking loop 19 again rests on theelevation of the locking loop cam 18. In its movement upward the lockingloop moves the pawl 11 in a direction to the r ght thereby rotating theratchet wheel 23 one notch.

Fixedly mounted on the shaft 40 is an indent wheel 25. An indent lever26 attached to element 10 is normally inserted in the indent of wheel25. A member 27 secured to the framework 12 by pivot 29 and biased in aclockwise direction by the spring 28 provides a latching means wherebythe indent lever 26 is held out of the indent of wheel 25 when the leveris withdrawn from the indent of the wheel. The insertion of the indentlever in the indent of wheel 25 prevents the rotation of the shaft 40.When element 10 is pushed downward, the indent lever 26 is preventedfrom being reinserted in the indent of wheel 25 by the member 27. Theshaft 40 is thereby free to move. A cog 30,

located on the cross-sectional face of wheel 25 at some distance fromthe indent, rotates the member 27 in a counter-clockwise direction. Thisaction releases the indent lever 26 so that it rests on the periphery ofthe wheel. 25. When the indent is again reached, after one completerotation of wheel 25, the indent lever 26 will fall in the indent of thewheel. The shaft 40 as a result ceases to rotate. This constructionaffords the operation of one complete revolution of the shaft 40 by thedownward movement of the element 10. The downward motion of element 10is produced by the forward motion of the roller 14 on the end of thepull bar 13 shown in Fig. 1. The bar 105 (Fig. 4) forming an integralpart of the framework 12 guides the pull bar 13. Means for preventingthe downward movement of element 10 when the operation of theanswer-back mechanism is not desired comprises a lever 16 pivoted to theframework 12 by the pivot 106 (shown in Fig. 1).

, the periphery of disc 99.

' or other 'over the line.

A depression of the key 1'? swings the lever 16 in an upward positionwhich in turn prevents the downward motion of element 10.

In Fig. 3, the construction of the rotatable answer-back means and thelocking means more fully illustrated. Mounted on the shaft 107 arelevers 85 to 89. One of the contact levers 89 is shown in this figure.It rests on To the disc contact lever is attached an intermediate lever'79. Lever 79 is connected to the locking lever 69 by means of the pivot52. A groove 53 is provided in the intermediate lever '79 through whichthe pivot 52 is passed. By constructing the groove 53 of suflicientsize, play is allowed for the locking lever 69 to move in the sending ofany desired message by the regular transmission apparatus of theprinter. The contact cam 39 closes the contacts 59 by the engagement ofcontact lever 49 with the indent of the contact cam. This engagementdepends upon whether the locking lever 69 is latched or unlatched.

In order to avoid the sending of signals as a result of the accidentaloperation of a key,

instrumentality employed for transmitting messages, a number of printingtelegraph systems provide disabling means for preventing, when desired,the transmission of signals from the keyboard. In Fig. 3, the disablingmeans comprise the circuit contacts 104. The closing of contacts'104shunts the circuit contacts 54 to 59. Means for transmitting theanswer-back signal regardless of the condition of the disabling meanscomprise the contacts 60 and 61 together with the armature 111. [he bar110 which is actuated by the element determines the position of thearmature 111. A downward movement of the element 10 pro duces acorresponding movement of bar 110 and results in the engagement ofarmature 111 and contact 61. When the armature 111 engages contact 60,the disabling means prevents the transmission of signals over the line.However, when the armature 111 engages the contact 61, the disablingmeans is rendered ineffectual.

The sending of messages in a number of printing telegraph systems ispredicated upon the transmission of signals or impulses in orderedsequence at definite intervals over the line. The motor at thetransmitting station must therefore rotate at a uniform speed. Wheninitially started, motors employed in these systems do not revolve at aspeed necessary for efficient transmission. A predetermined number ofrevolutions of the motor is required before the motor revolves at thedesired speed. To provide for the time required for the motor wheninitially started to attain sufficient speed before the transmission ofthe answer back signal, the periphery of cam 41 fixedly mounted on theshaft 40 controls contact 43. When the answer back mechanism is startedthe closing of contact 43 prevents the transmission of any signal overthe line by short circuiting the sending contacts The opening of contact43, however, permits the sending of the answer back message Theperiphery of cam 41 is so constructed that the motor must revolve apredetermined number of revolutions before the contact 43 is opened.

When contact 43 is closed and bar 116 pushed in a downward position sothat the armature 111 is in engagement with the contact 61, no signalpasses over the line circuit 108. When the contact 43 is opened,however, as a result of the depression in the cam 41, the impulse fromthe contact 59 is transmitted over the line circuit.

The. periphery of the disc 99 is irregular corresponding to the desiredimpulse to be transmitted by the contact 59. When the closing of contact59 is desired, an elevation on disc such as shown at is used, whereaswhen it is desired to have the contact remain open, a depression such asshown at 51 is employed. When the disc 99 has an elevation such as 50,the lever 89 moves in a counter-clockwise direction. This action in turnmoves the intermediate lever 79 to the. right. The trip lever 69 isrotated in a clockwise direction. When the contact cam 39 rotates, theelevation of the contact lever 49 falls in the depression of the contactcam 39 whereby the contact 59 is closed and an impulse sent over theline circuit 168. When the lever 89 rests on a depression such as 51 ofthe disc 99, the lever 89 is rotated in a clockwise direction on itspivot 107. This action moves the intermediate lever 79 to the left.Intermediate lever 79 actuates locking lever 69 in a counterclockwisedirection. In this position the locking lever 69 latches the contactlever 49 so that the elevation of the contact lever does not fall in thedepression of the contact cam 39. Contacts 59, therefore, remain openand no impulse passes over the line.

In Fig. 3, the section of the device is shown before the actuation ofthe answer-back mechanism. It will be observed that the lever 89 restsupon an elevation 119 of the disc 99 which is intermediate in heightbetween the elevation 50 and the depression 51. The height of theelevation together with the groove 53 aiford means whereby theanswer-back mechanism will not interfere with the locking means duringtransmission of messages from the teletypewriter keyboard.

The operation of the answer-back mechanism is initiated by sending acertain series of impulses over the line which actuate the selectionbars '72 (shown in Fig. 1). The end of pull bar 13 biased by spring 74falls momentarily into the alignment of slots and the bar rotates in aclockwise direction. The roller 14 on the other end of the pull barmoves element 10 downward. This action lowers the pawl 11 intoengagement with the ratchet wheel 23. Simultaneously, lever 26 iswithdrawn from the indent in wheel 25 and caught by the member 27. Theclutch throw-out lever 20 by the downward movement of the element 10 isdisengaged from the clutch throw-out cam 21. This latter action resultsin the engagement of driving clutch member 63 with driven clutch member62. The contact cams 35 to 39 and locking loop cam 18 then startrotating. The downward movement of the element 10 produces acorresponding movement of the bar 119. As a result of this actionarmature 111 engages with contact 61. However, due to closed contacts43, no impulse is sent over the line. After the contact cams havecompleted one revolution, the upward movement of the locking loop 19moves the ratchet wheel 23 over one notch by means of the pawl 11. Theperipheries of the discs 95 to 99 are irregular to correspond to thedesired set of impulses to be transmitted. An elevation which issufficiently high to actuate the respectively associated locking leversin an unlatched position causes the transmission of an impulse, while adepression insuring the latching of the contact lever by itsrespectively corresponding locking lever results in no impulse beingsent over the line. No impulses pass over the line circuit 108, however,since the contact 43 remains closed. As a result of the rotation ofshaft 40 the elevation of the cam 41 is passed after several rotationsof the contact cams. When this occurs, the contacts 43 become disengagedthus removing the short circuit from the sending contacts. The impulsesthen pass over the line circuit to the calling station. After a partialrotation of the shaft 40, the cog 30 moves the member 27 inacounter-clockwise direction whereby the lever 26 v is released. Thelever 26 then rests on the periphery of indent wheel 25. When the shaft40 has rotated one complete revolution, lever 26 is forced in thedepression of the indent wheel 25. Element 10 is moved upward. Theupward movement of element 10 disengages the pawl 11 from the ratchetwheel 23 and engages the throw-out clutch lever 20 with the throw-outclutch cam 21. As a result, clutch driving member 63 is disengaged fromclutch driven member 62. The contact cams stop rotating and the machineis in a condition for the transmission or reception of any desiredmessage. The calling station subscriber who does not desire theanswering-back mechanism on his own machine to operate, depresses hiskey 17 thus preventing the downward movement of element 10 by the upwardmovement of the bar 16.

Another modification provides for the actuation of the answer-backmechanism whenever the motor at the called station is started. lhedetails of this feature are shown in Figs. 5 and 6. Instead of the pullbar of the mechanism described above, a lever 93 is provided with aroller element as similar to the roller i l on the pull bar. The lever93 is biased by the spring 100 in a clockwise direction. The preventionkey mechanism comprises a lever 84, a spring 91, the convolution ofwhich surrounds the lever 84, the spring biasing this lever to the left,a member 82 attached to the lever 84 by the pivot 90, the indent holderalso being pivoted to the framework by the pivot 83 and a knob 81 formanually controlling the movement of lever 84. The member 82 is soconstructed and pivoted that a counter-clockwise movement releases theindent lever 26. The downward movement of the element 10 actuates therotation of the answer back discs for one complete revolution in amanner similar to that described above. Several methods of starting themotor of a tele graph typewriter remotely are well known and are notdescribed here. When the motor M of the called station is not energized,the element 10 is in a downward position due to the clock wise bias ofspring 100 creating a pressure of the roller element 94 of the lever 93.As a result of the downward position of the element 10, the indent lever26 remains out of the depression of the indent wheel 25 and is latchedout of the depression by member 82. The pawl 11 is engaged with theratchet wheel 23 and the throw-out clutch lever 20 is disengaged fromthe throw-out clutch cam 21. The answer back mechanism is ready to startfunctioning upon the starting of the motor. An electromagnetic device 92is connected in parallel with the motor circuit 109.

When the motor is started either remotely or locally, electromagnet 92attracts the lever 93 rotating it in a counter-clockwise direction.

The answer-back mechanism then operates in a manner described above. Theindent lever 26 releases from the indent holder by the cog 30 and ceasesto operate after one complete revolution of the shaft 10. Referring toFig. 3, the elevation on cam ll is so constructed that the answer-backimpulses are not transmitted over the line until the printer motor hasattained a speed sufficient for the efilcient transmission of theseimpluses. When the motor is stopped, the lever 93 is released from themagnet 92, the roller element 94 moves the element 10 downward and thedevice is in condition for the transmission of another answer-backmessage.

If it is desired to start the motor without the transmission of theanswer-back signal the knob 31 of the prevention key is pulled to theright while turning the switch to start the motor. This action rotatesmember 82 in a counterclockwise direction around the pivot 83. Theholder releases the indent lever 26 and that lever is forced in theindent of wheel 25 upon the upward movement of member 10. When the motoris started, the magnet 92 is energized whereby the lever 93 is with itsroller 94 rotated in a counter-clockwise direction. The ele- .ent itmoves upward and the indent member 26 falls in the depression of wheel25. The answer-back mechanism is thereby prevented from operating.

What is claimed is:

1. In a printing telegraph system comprising two stations, a lineconnected therebetween, a plurality of circuit contacts at one of saidstations and locking means associated therewith, said locking meanscontrolling said circuit contacts for the transmission of impulses oversaid line, transmitting means, said transmitting means controlling saidlocking means, a rotary answer-back device at said station directlyconnected to said locking means for transmitting a predetermined signalover said line in response to a signal from the other of said stationsthe operation of said device being independent of said transmittingmeans.

2. In a printing telegraph system comprising a calling station, a calledstation. a line connected therebetween, a plurality of circuit contactsat said called station and locking means associated therewith, saidlocking means controlling said circuit contacts for the transmission ofa signal over said line, transmitting means, said transmitting meanscontrolling said locking means, an answer-back device at said calledstation comprising a plurality of rotatable cams connected directly withsaid looking means, said rotatable cams being actuated by a signal fromsaid calling station the operation of said device being independent ofsaid transmitting means.

3. In a printing telegraph system comprising a station, a line connectedthereto, a plurality of circuit contacts at said station and lockingmeans associated therewith, said locking means controlling said circuitcontacts for the transmission of a signal over said line, transmittingmeans, said transmitting means controlling said locking means, a deviceat said station for transmitting an answer-back signal comprising aplurality of rotatable cams directly connected with said locking means,said rotatable cams being actuated by a signal on the line and means atsaid station for preventing the transmission of said answer-back signalwhen desired the operation of said device being independent of saidtransmitting means.

4. In a printing telegraph system comprising a calling station, a calledstation, a line connected therebetween,. a plurality of circuit contactsat said called station, a locking lever associated with each of saidcontacts, said locking lever controlling its respectively associatedcircuit contact, transmitting means, said transmitting means controllingsaid locking levers for the transmission of a message over said line, ananswer-back device at the said called station for the transmission of apredetermined message, said device comprising a disc directly associatedwith each of said locking levers and in engageable relation therewith,the peri hery of said disc operating its respectively associated lockinglever, the periphery of said disc being irregular in form to correspondto the desired predetermined message to be transmitted and meansresponsive to a signal from the said calling station for rotating saiddiscs and continuing the rotation during the transmission of saidpredetermined message the operation of said device being independent ofsaid transmitting means.

5. In a printing telegraph system comprising a calling station, a calledstation, a line connected therebetween, a plurality of contacts at saidcalled station, a locking lever associated with each of said'contacts,the opening and closing of said contacts being determined by theposition of said locking lever, transmitting means, said transmittingmeans controlling said locking levers for the transmission of a messageover said line, an answer-back device at said called station comprisinga disc directly associatcd With each of said locking levers, theperiphery of said disc being irregular in form and controlling theposition of its respectively associated locking lever, means responsiveto a signal from said calling station for the rotation of said discs forone revolution and means for discontinuing the rotation thereafter theoperation of said de- Vice being independent of said transmitting means.

6. In a printing telegraph system comprising a calling station, a calledstation and a line connected therebetween, a plurality of circuitcontacts for producing a series of impulses in ordered sequence over theline, a locking lever associated with each of said circuit contacts, theposition of each of said levers determining the opening and closing ofits respectively associated contact, transmitting means, saidtransmitting means controlling said locking levers for the transmissionof a message over said line, an answer-back device comprising a disccorresponding to and in engageable relation with each of locking levers,the periphery of each of said discs controlling the position of saidlooking levers, said periphery being irregular in form to correspond toa desired predetermined answer-back signal to be transmitted, meansresponsive to a certain signal from said calling station for causing therotation of said disc and means for continuing the rotation for onecomplete revolution and for discontinuing the rotation thereafter theoperation of said device being independent of said transmitting eans.

'7. In a printing telegraph system, an answerback device comprisingcontact cams, a motor for rotating said cams, locking levers associatedwith each of said contact cams, circuit contacts controlled by saidcontact cams and said locking levers, a disc associated Witheach of saidlocking levers, the periphery of said disc determining the operation ofsaid locking lever, means responsive to a predetermined signal forrotating said motor for causing the rotation of said disc when saidmotor is started, means for deferring the transmission of saidanswer-back message until said motor has rotateda predetermined numberof revolutions, and means for completing the transmission of theanswerback message. Y

8. In a printing telegraph system, comprising a calling station, acalled station and a line connected therebetween, an answer-back deviceat said called station comprising contact cams, a motor for driving saidcams, a locking lever associated with each of said contact cams, cir-,cult contacts controlled by said contact cams and said locking leversfor the transmission of the message over the line, a disc'associatedwith each of said locking levers, the periphery of each of said discsbeing irregular in form and determining the operation of itsrespectively associated locking lever, means responsive to a signal fromsaid calling station for starting said motor, means actuated by thestarting of said motor for causing the rotation of said discs, means fordeferring the transmission of said answer-back signal until said motorhas revolved a predetermined number of revolutions, means for continuingthe rotation of said discs for the completion of one revolution, andmeans for discontinuing the rotation of said discs thereafter.

9. In a printing telegraph system comprising a calling station, a calledstation and a line connected therebetween, an answer-back device at saidcalled station comprising a plurality of contacts, a contact cam, acontact lever, and a locking lever associated with each of saidcontacts, the opening and closing of each of said contacts beingcontrolled by the engagement of its respectively associated contact camand contact lever, the engagement of said contact cam and contact leverbeing determined by the position of its associated locking lever,transmitting means, said transmitting means controlling said lockinglevers for the transmission of a message over said line, an answer-backdevice comprising a disc associated with each of said locking levers,the periphery of said disc being irregular in form and in engageablerelation with its re spectively associated locking lever, stepping meansfor the rotation of said discs, means for rotating said discs upon thereception of a certain signal from said calling station, means forcontinuing the rotation of said discs for one revolution, means fordiscontinuing the rotation thereafter, and means at said called stationfor preventing the transmission of the answer-back.

signal when desired, the operation of said device being independent ofsaid transmitting means.

10. In a printing telegraph system comprising two stations and a lineconnected therebetween, one of said stations comprising a remotelycontrolled device for transmitting an answer-back signal to the other ofsaid stations, an instrumentality, transmission means actuated by saidinstrumentality for sending signals over said line, disabling means forrendering said transmission means inoperative, and means fortransmitting said answer-back signal independent of said disablingmeans.

11. In a printing telegraph system comprising two stations and a lineconnected therebetween,

one of said stations comprising a remotely controlled device fortransmitting an answer-back signal to the other of said stations, akeyboard, transmission means actuated by the keys of said keyboard forsending signals over said line, disabling means for rendering saidtransmission means inoperative and means for transmitting saidanswer-back signal independent of said disabling means.

12. In a printing telegraph system, a rotary answer-back device, a motorfor rotating said device, and means for deferring the transmission of ananswer-back signal until said motor has rotated a predetermined numberof revolutions.

13. In a printing telegraph system comprising a station and a lineconnected thereto, said station comprising contact cams, a motor forrotating said cams, locking levers associated with each of said contactcams, circuit contacts controlled by said contact cams and said lockinglevers, means for transmitting a signal over said line, said meanscontrolling said locking lever, and a device for transmitting ananswer-back signal, said device being actuted by the starting of therotation of said motor and said answerback signal being transmitted bythe opening and closing of said contacts.

14. In a printing telegraph system comprising a station and a lineconnected thereto, said station comprising a rotary answer-back device,a motor for rotating said device, means responsive to a signal over saidline for starting said motor, means responsive to the starting of saidmotor for actuating said answer-back device and means for deferring thetransmission of an answer-back signal until said motor has rotated apredetermined number of revolutions.

EDWARD F. WATSON.

